1. Field of the Invention
The present invention relates to a fabric arrangement and method for controlling fluid flow and, more particularly, to a fabric arrangement and method for controlling fluid flow which may be utilized with friction elements. In one embodiment, the invention provides a method and system for forming a frictional material having a plurality of slots with an optional chamfer and/or raised rib.
2. Description of Related Art
In clutches, brakes, automatic transmissions, limited slip differentials, hoists and similar friction power transmission and energy absorption devices, there is generally provided one or more sets of cooperating members, in which one of the cooperating members drives the other. It is not uncommon for these cooperating members to move in a cooling medium or liquid, which is generally some type of lubricating oil, and frequently the oil is force circulated about and between the engaging surfaces of the cooperating members so as to continuously lubricate and cool them. In order to accomplish circulation of the cooling medium within blocker rings, clutch plates, transmission bands and the like, the prior art has provided grooves or slots directly in the engaging surfaces of one or both of the cooperating members or in friction material affixed thereto. For example, such a friction material may be a brass coating or a paper liner as seen in U.S. Pat. No. 4,267,912 to Bauer et al., U.S. Pat. No. 4,878,282 to Bauer, and U.S. Pat. No. 4,260,047 to Nels.
Forming grooves within the friction material of cooperating members not only adds complexity to the manufacture of such friction material and the power transmission-absorption device, but also is limited in its ability to circulate cooling medium therethrough. In order to reduce or eliminate the hydrodynamic friction stemming from oil or cooling medium lying on the surface of the friction material engaging the driving member, an improved friction material for circulating the cooling medium is required, especially one which may be varied according to desired parameters.
Prior art friction materials also include certain pyrolytic carbon friction materials as seen in U.S. Pat. No. 4,700,823 to Winckler and U.S. Pat. No. 4,291,794 to Bauer. In such friction material, a meshed cloth substrate formed of carbon fibers is provided with a coating of carbon or other material being deposited on the fibers by chemical vapor deposition. This type of friction material has the characteristic of a relatively open mesh which allows ready penetration by an adhesive for improved bonding, as well as a certain degree of porosity therethrough. However, as pointed out in the '794 patent, grooving of such material is still provided in order to permit the flow of the cooling fluid between the friction faces of the cooperating members of the power transmission or energy absorption assembly. This type of friction material also does not easily provide highly bonded fibers at a friction surface of the material nor does it achieve a highly controlled texture as needed. Moreover, it has been found that such friction material is difficult to compress to a desired thickness, such as during the process of bonding it to a member.
It is also seen that such pyrolytic friction material utilizes as its substrate a plain weave of the type illustrated in FIG. 6, where both the fill and warp yarns of the material contact the cooperating element. Such an arrangement leads to increased wear of the friction material due to the effect on the yarns oriented perpendicularly to the direction of motion for the cooperating element. Therefore, an additional desired feature not found in prior art devices is a friction surface texture which reduces wear on the friction material.
U.S. Pat. No. 4,878,282 illustrates a method for producing friction plates, synchronizing blocker rings and similar structures which use friction lining material applied as a continuous member onto a support where the ends of grooves are opened by removal of the friction lining material which close the grooves. This required several manufacturing steps, including cutting the material, assembling the material to the support, densifying the material once it was on the support and then trimming off a portion of the material. Unfortunately, the use of this type of process created, for example, about 20% scrap material.
Therefore, a further desired feature not found in prior art systems and methods is to provide a material and process which reduces the amount of scrap, yet which provides the advantages of a grooved material, including facilitating improving the engagement between the frictional support on which the material was mounted and a mating frictional member.